1. Field of the Invention
The present invention relates to a treatment tool that is used in conjunction with an endoscope.
Priority is claimed on Japanese Patent Application No. 2007-144873, filed May 31, 2007, the contents of which are incorporated herein by reference.
2. Description of Related Art
Conventionally, a treatment tool that is used in conjunction with an endoscope, for example, an incision tool that is used to incise biological tissue is known in which, normally, wires which form a knife portion are housed inside a flexible sheath or else are positioned alongside an outer surface of the circumferential wall of the flexible sheath. When the biological tissue is actually to be incised, a portion of each wire is made to expand diametrically so as to protrude some distance from the outside of the flexible sheath. In this state, an incision is performed by pressing the wires against a predetermined position of the biological tissue which is to be incised while supplying high-frequency current to the wires (see Published Japanese Translation No. 8-509894 of the PCT International Publication, and Japanese Unexamined Patent Application, First Publication No. 2004-73582).
However, in a conventional treatment tool in which the wires are expanded when an incision is to be made, when a portion of the wires is expanded to make an incision, the problem has arisen that the wires become twisted or bent and cannot be expanded to a desired shape, which has resulted in the incision direction being unstable. Particularly when this expansion is accompanied by a rotational movement of the wires, the wires collapse so that there is a possibility that the operation will not be completed.